1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device, which can prevent peeling or cracking of the SOG (spin on glass) layer used for planarization of an interlayer insulating layer in a multi-level metal layered structure.
2. Description of the Prior Art
In a semiconductor device having multi-level metal layered structure, an interlayer insulating layer is formed to insulate between the lower metal layer and the upper metal layer. The interlayer insulating layer consists of a plurality of insulating layers, including a SOG layer to improve a planarization of surface. The SOG layer has good surface planarization, however, it contains a large amount of moisture therein due to its strongly hydrophilic property. Therefore, an insulating layer is formed before forming the SOG layer to prevent penetration of moisture contained in the SOG layer into the lower metal layer.
However, moisture in the atmosphere is absorbed into, or adsorbed onto, the insulating layer after forming the insulating layer according to the condition of the insulating layer. The moisture contained in the insulating layer causes peeling or cracking of the SOG layer when the SOG layer is cured.
FIGS. 1A and 1B are sectional views for illustrating a conventional method of manufacturing a semiconductor device.
Referring to FIG. 1A, a first interlayer insulating layer 2 is formed on a silicon substrate 1, and a lower metal layer 3 is then formed on the first interlayer insulating layer 2 by a metal wiring process. A first insulating layer 4 is formed on the first interlayer insulating layer 2 including the lower metal layer 3.
In general, the first insulating layer 4 is a TEOS oxide layer, a SiH.sub.4 oxide layer or an extra-silicon oxide layer which is formed by a plasma chemical vapor deposition method. During the waiting time for the next process, micro waterdrops 7 are created on the surface of the first insulating layer 4 because of property of the first insulating layer 4. That is, the TEOS oxide layer absorbs moisture therein, SiH.sub.4 oxide layer absorbs and adsorbs moisture therein and the extra-silicon oxide layer adsorbs moisture on the surface thereof.
Referring to FIG. 1B, a SOG layer 5 is coated on the first insulating layer 4, and a curing process is then performed. An second insulating layer, an upper metal and a second interlayer insulating layer (not shown) are sequentially formed on the SOG layer 5. At high temperature, the waterdrops 7 created on the first insulating layer 4 are vaporized, therefore, a portion of the SOG layer 5 peels off or cracks due to the vapor pressure. As shown in FIG. 1B, a defective portion 6 of the SOG layer 5 results after the curing process.
The defective portion 6, as described above, results more excessively at the boundary between the SOG layer 5 and the lower metal layer 3. The peeling and cracking of the SOG layer 5 become factors that impede an effectiveness of subsequent processes. The greater the time interval from completion of forming the first insulating layer 4 to commencement of forming the SOG layer 5, the greater the likehood of forming these defective portions 6.